Write the basic phonetics for each letter of the English alphabet on the first page of a notebook, including the sound of the letter name and the sound the letter makes when pronounced alone. Customize this list for your own personal reference. For example, the pronunciation for the letter "K" is typically written "kei," but if writing "kay" helps you remember the sound better, use that instead. Include any letter combinations that normally give you problems, such as "PH sounds like F."
Divide your notebook into sections for words based on a method that you will be able to remember and reference easily. This could be simply leaving a few pages for each letter of the alphabet, or having separate sections for nouns, verbs, adjectives, adverbs and prepositions.
Bring your notebook, pencil and pocket voice recorder when you go out. When you mispronounce a word and are corrected by someone, immediately write the word in the appropriate place in your notebook, then say it correctly into your voice recorder to save for future reference. Another option is to ask a native speaker to say the word for you. Some might find this uncomfortable, but many native speakers will not mind helping someone trying to learn the language, and collecting voice recordings of difficult words correctly pronounced by native speakers will be a valuable resource.
Review the words you added to your notebook and recordings every night, and practice saying them out loud. If the word is an exception, write that exception down in your notebook. For example, "The EA in 'head' is pronounced 'eh', while the EA in heat is pronounced 'ee.' "
Quiz yourself on all of the material you have collected at the end of each week. Read the words in your notebook, say them out loud, then listen on your recorder to see if you were correct. Retaining information relies on repetition and use, and the more material you add to your collection, the easier it is to forget the phonics you learned in the beginning. Constantly go back and refer to old notes until they are ingrained in your memory.